var b = require('./b')
var fs = require('fs')
console.log(b.add(10,20))
console.log(b.foo)
b.readFile('./a.js')

fs.readFile('./a.js',function (err,data) {
    if (err){
        console.log('读取文件失败');return
    }
    console.log(data.toString())
})